Plant Cell Reports最新文献

Phosphorus deficiency is a critical abiotic stress that limits crop productivity, severely constraining plant photosynthesis by inhibiting light reactions and carbon assimilation. Methyl jasmonate (MeJA), as a key stress signaling molecule, plays a central regulatory role in plant adaptation to low-phosphorus environments. This article systematically reviews the physiological and molecular mechanisms by which exogenous MeJA alleviates photosynthetic inhibition under low-phosphorus stress, with a focus on its integration of phosphorus starvation and jasmonate signaling pathways through the PHR1 (PHOSPHATE STARVATION RESPONSE 1)-JAZ-MYC2 signaling module. This, in turn, coordinates a multi-layered network involving the regulation of photosynthetic enzyme activity, antioxidant defense, and phosphorus uptake and recycling. The article also explores potential approaches for improving crop phosphorus efficiency through the jasmonate signaling pathway. This review aims to provide a theoretical foundation for understanding plant phosphorus-hormone interaction mechanisms and offer new insights for stress resistance regulation and genetic improvement in crops.

Key message: The cytokinin regulatory system (CRS) is important for plant adaptation to adverse environmental conditions, including drought and heat stress. CRS represents a promising biotechnological target to improve crop tolerance to these stresses. Drought and heat are widespread natural phenomena leading to stress in plants and a significant yield reduction in crop plants. Tolerance of drought and heat determines the productivity of major crops. The global climate forecast predicts further temperature increase and worsening water shortage in the very near future. Plants can withstand heat stress and water scarcity using their adaptive hormonal system. Among the plant hormones, cytokinins (CKs), which are best known for their numerous functions in regulating growth and development, play a significant role in plants' responses to heat and water stress. This review summarizes the effects of CK on drought and heat tolerance in common agricultural plants, and strategies to protect these plants are described. Particular attention is paid to biotechnological approaches targeting the cytokinin regulatory system (CRS) to preserve crop phenotype and yield under stress conditions. Interestingly, CKs have been reported to improve drought/heat resistance both by increased and decreased signaling. We propose a rational explanation for this apparent paradox of CK action. This review aims to be helpful to plant biotechnologists and genetic engineers in selecting suitable CRS targets that could serve as tools to generate new drought- and heat-tolerant crop varieties.

Key message: The GH10 endoxylanase XccXynB from Xanthomonas campestris pv. campestris (Xcc) functions as a PAMP, triggering PTI responses and enhancing disease resistance in plants, in addition to its polysaccharide degradation capability. Plant pathogens of the Xanthomonas genus are capable of infecting a wide array of economically important plant species. Among their virulence factors, the GH10 family xylanase, XynB, is typically responsible for the predominant extracellular xylanase activity. However, the detailed biochemical characteristics of this enzyme in most Xanthomonas pathogens remain insufficiently understood. In this study, we conducted a comprehensive characterization of the enzymatic and immunogenic properties of XynB from Xanthomonas campestris pv. campestris (Xcc). We found that XccXynB functions as an endoxylanase with a K_m of 16.93 ± 4.93 (mg/mL) and K_cat of 1.42 ± 0.17 (min⁻¹), primarily producing xylooligosaccharides (XOSs) ranging from xylobiose (X2) to xylohexaose (X6). Site-directed mutagenesis confirmed that residues E138 and E254 are essential for its catalytic activity. Furthermore, we found that XccXynB can act as a pathogen-associated molecular pattern (PAMP) in the model plants N. benthamiana and A. thaliana, triggering immune responses such as reactive oxygen species (ROS) burst comparable to the elicitor Flg22, without inducing cell death. Heterologous expression of XccXynB in A. thaliana led to constitutive immune activation and significantly enhanced disease resistance, with the in planta bacterial population of Pst DC3000 being reduced to ~ 80%. Taken together, these findings could provide a rationale for developing novel strategies against Xanthomonas diseases by targeting the conserved xylanase function or utilizing the protein as an immunogen.

Key message: Cis-natural antisense transcript ELENA19 attenuates PAMP-triggered immunity by modulating ABA- and PAMP-inducible UGT71B6 expression, resulting in increased ABA levels and reduced ET-dependent flg22-induced callose deposition in Arabidopsis. Long noncoding RNAs (lncRNAs) have emerged as crucial regulators of various biological processes. However, the roles of lncRNAs in pathogen-associated molecular pattern (PAMP)-triggered immunity (PTI) remain largely unexplored in plants. Based on our previous custom lncRNA array analysis of Arabidopsis seedlings treated with PAMPs (elf18 and flg22), we identified a novel ELF18-INDUCED LONG NONCODING RNA, ELENA19. In this study, we characterized the function of ELENA19 as a natural antisense transcript of UDP-glycosyltransferase 71B6 (UGT71B6), which is responsible for the glycosylation of abscisic acid (ABA). ELENA19 expression was rapidly upregulated upon treatment with ABA or PAMPs (flg22 and elf18). Among the genes neighboring ELENA19, only UGT71B6 was responsive to both ABA and PAMP treatments. UGT71B6 expression was significantly attenuated in ELENA19-overexpressing (OX) plants compared to wild-type (WT) plants after PAMP or ABA treatment. ELENA19 OX plants were hypersensitive to ABA during germination and had higher endogenous ABA levels than WT plants, suggesting that ELENA19 down-regulates UGT71B6 expression and enhances endogenous ABA levels. Flg22-triggered callose deposition was reduced, and the expression of ethylene (ET)-dependent Flg22-induced genes was significantly down-regulated in ELENA19 OX plants compared to WT plants, confirming the antagonistic interaction between ABA and ET signaling in the flg22-mediated immune response. These results demonstrate that ELENA19 attenuates PAMP-triggered immunity by modulating UGT71B6 expression.

Key message: Genome-wide analysis coupled with spatiotemporal profiling identified CmMYC25 as a key regulator. It functions as a transcriptional co-activator to synergistically enhance CmMYB6-mediated anthocyanin biosynthesis in chrysanthemum petals. Myelocytomatosis (MYC) transcription factors (TFs), belonging to the basic helix-loop-helix (bHLH) superfamily, play a crucial role in regulating various physiological processes in plants. However, research on the MYC gene family in Chrysanthemum morifolium, one of the primary cut flowers, remains scarce. Here, we identified 28 CmMYC genes via genome-wide analysis and classified them into three subfamilies based on phylogenetic relationships. Collinearity analysis suggested expansion driven by both ancient whole-genome duplication (WGD) events and recent segmental duplications. Promoter analysis uncovered a variety of regulatory elements, with hormone-responsive motifs being the most predominant. Phylogenetic clustering indicated that Group B members are orthologous to anthocyanin regulators. Among them, CmMYC25 was prioritized for further analysis, as its expression pattern was perfectly synchronized with anthocyanin accumulation during flower development. CmMYC25 was localized to the nucleus but lacked transcriptional activation activity. Notably, yeast one-hybrid assays indicated that CmMYC25 does not directly bind to the promoters of anthocyanin biosynthetic genes. Instead, it physically interacts with CmMYB6, a central activator of anthocyanin biosynthesis. Dual-luciferase assays confirmed that CmMYC25 functions as a co-activator, synergistically enhancing the transcriptional activity of CmMYB6 on downstream target genes. Functional characterization verified that CmMYC25 acts as a positive regulator of floral pigmentation, as its overexpression significantly increased anthocyanin accumulation, while suppression reduced pigmentation. These findings provide insights into the evolution of CmMYC genes and elucidate the co-activator mechanism of CmMYC25 in regulating flower pigmentation.

Heat stress significantly affects plant growth by compromising cellular membranes. This review examines the mechanisms by which plants perceive heat at the plasma membrane, initiate lipid changes, and activate protective proteins to maintain membrane integrity. The investigation focuses on essential signaling pathways that encompass heat shock transcription factors, phospholipid messengers, reactive oxygen species (ROS), calcium, and mitogen-activated protein kinases (MAPKs). We underscore lipid modification, especially in plasma and thylakoid membranes, to preserve membrane fluidity during thermal stress, alongside the functions of small heat shock proteins, Hsp70, and Hsp90. We examine ways to enhance thermotolerance, including conventional breeding, genetic engineering, and genome editing focused on desaturases, membrane lipids, and heat shock protein regulators. The relationship between antioxidant and osmolyte responses, along with their interplay with salinity and drought stress, is analyzed. Significant research deficiencies are recognized, especially regarding the relationships among field performance, organelle interactions, proteostasis, and lipidomics. This review synthesizes novel notions of inter-organelle coordination, thermomemory, and sophisticated biophysical imaging tools to investigate membrane dynamics and thermotolerance, presenting new opportunities for cultivating crops adaptable to increasing temperatures.

Key message: SmCAD4 orchestrates a synergistic defense against drought by simultaneously fortifying tissues with lignin and optimizing the root system for enhanced water uptake, a novel integrated mechanism. Drought stress is a primary environmental factor limiting the productivity and medicinal quality of crops such as Salvia miltiorrhiza. While cell wall lignification represents a fundamental adaptive strategy, the specific transcriptional networks coordinating these responses under water deficit remain largely uncharacterized. In this study, we identify the cinnamyl alcohol dehydrogenase gene SmCAD4 as a pivotal regulator of drought resilience in S. miltiorrhiza. Utilizing DNA affinity purification sequencing (DAP-seq) alongside molecular interaction assays including Y1H, Dual-LUC, and EMSA, we establish that SmCAD4 is a direct downstream target of the transcription factor SmDof32. SmDof32 specifically binds to a conserved AAAAG motif within the distal promoter region of SmCAD4 to activate its transcription, thereby defining a complete stress-responsive module. Overexpression of SmCAD4 significantly enhances plant survival under severe water deficit by triggering a synergistic dual mechanism. Biochemically, SmCAD4 promotes lignin deposition in vascular tissues to fortify cellular structures and improve water retention; morphologically, it drives the development of a robust root system architecture with increased length and branching for enhanced water acquisition. Furthermore, the heterologous expression of SmCAD4 in Arabidopsis thaliana consistently confers improved osmotic and drought tolerance, confirming its functional potential across different plant systems.Query This work deciphers a novel molecular pathway integrating biochemical reinforcement with morphological adaptation, highlighting the SmDof32-SmCAD4 module as a prime target for the genetic improvement of stress resilience in medicinal plants and broader agricultural crops.

Key message: This study elucidates endoplasmic reticulum (ER) stress response mechanisms in Brassica campestris at the gene level using high-throughput transcriptome analysis. The productivity of Brassica campestris is severely limited by adverse environmental conditions that trigger ER stress and disrupt cellular homeostasis. However, the molecular mechanisms underlying ER stress responses in B. campestris remain poorly understood. In this study, tunicamycin (TM) and tauroursodeoxycholic acid (TUDCA; TU) were applied to induce and alleviate ER stress, respectively, followed by transcriptome profiling through high-throughput RNA sequencing. A total of 11,728 differentially expressed genes (DEGs) were identified across distinct pairwise comparisons. These DEGs were significantly enriched in GO terms related to oxidative stress response, protein processing in the ER, unfolded protein binding, and protein folding, as well as activated pathways associated with ROS signaling, calcium signaling, and flavonoid biosynthesis. Hierarchical clustering analysis grouped these DEGs into five clusters, of which C1 showed higher expression associated with TM and TU, C2 showed downregulation during ER stress, and C3 showed higher expression in TM treatment. Among DEGs, 351 transcription factors (TFs) were identified under ER stress, with the most abundant families being bZIP (57), NAC (83), MYB (113), HSF (26), and WRKY (72). Weighted gene co-expression network analysis (WGCNA) further identified three co-expression modules (green, brown, and turquoise) comprising 60 key genes, including four unique genes (BraC03g015140, BraC05g046930, BraC08g032210, and BraC09g046280), and 56 hub genes overlapping with DEGs. The identified 60 candidate genes are involved in protein quality control, chaperone activity, ubiquitin-mediated degradation, redox regulation, vesicle trafficking, and metabolic adjustment. Therefore, this study provides a comprehensive transcriptional landscape of ER stress responses in B. campestris, identifies key regulatory genes for functional validation, and offers valuable insights into improving stress resilience in Brassica crops.

Unlike annual herbaceous species, trees have long juvenile periods, and several years or even decades have to be passed before their first flowering occurs, which is undesirable for both industrial and breeding purposes. This review describes various applications of grafting to reduce the time to first flowering in woody species. Dwarfing rootstocks commonly used in agriculture often induce precocious flowering in scions. Possible molecular mechanisms underlying rootstock-induced early flowering in grafted trees are considered. Another traditional approach is grafting juvenile scions onto mature trees, which has been used to induce precocity in a variety of woody species. The main drawbacks of grafting on both dwarfing and mature rootstocks are moderate degree of precocity and varying efficiency for different rootstock-scion combinations. Modern biotechnological approaches to induce early flowering are based on the overexpression of floral activators through either genetic transformation or recombinant viruses. Transgenic rootstocks expressing graft-mobile floral activators have been utilized to induce early flowering in non-transgenic scions of several woody species. Different transgrafting studies demonstrated contrasting efficiency of this approach, apparently due to an insufficient amount of floral inducer being provided by the transgenic rootstock to the scion in certain experiments. Methods for increasing the amount of floral inducer in grafted scions are thoroughly described. Another approach to induce precocity in trees is VIF, or virus-induced flowering, which is based on the use of viral vectors to systemically infect the plant and express floral activators. Grafting has promising yet largely unexplored potential in VIF and other applications that utilize viral vectors.

MYB transcription factors play a pivotal role in plant responses to cold stress. However, the underlying regulatory mechanisms in eggplant (Solanum melongena) remain unclear. In our previous study, based on transcriptomic analysis, we identified a MYB transcription factor as a core regulatory gene involved in cold stress responses in eggplant. In this study, we isolated and cloned SmMYB88 from eggplant. SmMYB88 was localized to the nucleus and exhibited transactivation activity. Heterologous overexpression of SmMYB88 in Arabidopsis thaliana enhanced the plant's cold tolerance. SmMYB88 specifically bound to the promote elements of SmGST and SmGPX. Furthermore, the interaction between SmMYB88 and SmERF1 further up-regulated the expression of SmGST and SmGPX genes. The up-regulated SmGST and SmGPX enhanced the plant's capacity to scavenge reactive oxygen species (ROS) by increasing glutathione metabolism and corresponding enzyme activities, thereby improving the plant's tolerance to cold stress. Additionally, overexpression of SmMYB88 significantly increased the expression levels of ICE1, CBFs, and COR47 in Arabidopsis (p < 0.05), suggesting that SmMYB88 may enhance plant cold tolerance by regulating the expression of CBF network genes. Therefore, this gene may serve as a potential target for genetic engineering to improve cold tolerance in eggplant.